Chuck



O. BEARD June 1932.

CHUCK Filed pril 4, 1

Patenteol June 14,

Uhlllhl STATES LAJJRENCE G. BEARD, OF LANCASTER, PEITNSYLVANIA CHUCK Application filed April 4,

My invention relates to chucks for rcamers,

ls and similar tools and particularly to that type of chucks employing a pair of oppositely arranged loosely mounted gripping aws.

The object of the invention is to provide a pair or" chuck aws which will readily line. up or center cylindrically shanked tools.

Another object is to provide an improved =':onstruction or j aws, whereby the cylindrical portion of the tool shank will be frictionally gripped and the squared end thereof will be positively gripper when the tool turns in the jaws under excessive driving pressure, incident to use on heavy work.

A further object is to provide a four point yielding bearing and two point driving bearing for gripping the round and square 'iortions oi the tool snank respectively.

A. still further object of the invention is to provide an improved arrangement and construction of oppositely disposed chuck jaws adapted to be moved to closed position with their acting faces maintained in parallel relation to each other.

I accomplish the above mentioned and other related objects by the improved construction hereinafter described and claimed.

Of the accompanying drawing forming a part of this specification:

Figure 1 represents a longitudinal section of a chuck having jaws embodying my invention applied to the shank of a reaming tool;

Figure 2 is a longitudinal sectional view taken through Figure 1, with the reaming tool removed;

Figure 3 is similar to Figure 1 showing the spring means for maintaining parallel alinementof the aws;

Figure is a view similar to that shown in Figure 3, with the aws in open position and cap removed;

Figure 5 a transverse section on the line of Figure 1, with the tool shank removed Figure 6 is a side view of one of the jaws; and

Figure 7 is an end view of one of the jaws.

Referring more particularly to the drawing wherein the same reference characters in- 1931. Serial No. 527,783.

dicate like parts in all the figures, 1 denotes the body of my improved chuck which is of cylindrical shape and formed at its outer or forward end with a nose portion 2. The body 1 is threaded eXteriorly as at 3 for engagem ment with the internally threaded cap memher 1, and is also provided with a cent-rally disposed bore or passage 5, adapted to receive the reduced threaded end 5 of the customary driving shaft or shank 6 by means or which the chuck is attached to a source of power, such as a drill press, not shown.

The nose portion 2 of the body 1 is longitudinally slotted in a central plane as at T, to form the jaw receiving prongs or portions to 8 between which a pair of 9 hereinafter described lit. The nose end is of trusto conical taper to fit the correspondingly tapered end 10 of the cap or clamping sleeve member The jaws 9 have fiat exterior bearing surfaces 11 which slidably it against corresponding surfaces 12 formed on the inner faces of the prongs 8 and a coiled spring member 13 which connects the two jaws to gether serves to resiliently maintain the latter in the slot 7 in normal open or Figure 4: position. The body of this spring lies within the enlarged central chamber of bore 14, formed in the body of the chuck, and the straight ends 15 thereof extend outwardly through narrow slots or grooves 16 into the longitudinal slot 7 when they are attached to the inner ends of the jaws.

In accordance with the present invention, the inner clamping face of each jaw is formed at its lower end portion with an elongated longitudinal substantially V-shaped recess or groove 18 of uniform width and depth throughout its length. The flat smooth sides 19 of the grooves diverge from each other at 9 an angle substantially that of a right angle and present a four point yieldable gripping bearing adapted to conform to and line up or center the cylindrical shank portion 20 of the rcamer or other tool 21, when the latter is inserted in the chuck and the cap member 4 is screwed home, in an obvious manner. To simplify machining the groove 18 may be slightly flattened at the point where the inner edges of the sides 19 approach each other, as best illustrated in Figure 2.

The inner end of each jaw 9 is also formed with a second comparatively short longitudinal substantially V-shaped recess or groove 22 which is in effect a continuation of the groove 18. The only substantial difference between the inner and outer grooves .22 and 18 is that the latter is cut deeper than the former, the width and depth of each groove 22 being uniform throughout but'slightly less than;v that of the grooves 18. The sides 23 of the grooves 22, also extend at substantially right angles to each other and provide a two point gripping bearing for the squared end 24; of the tool shank,..the depth and. .widthof the grooves 22 adapting them. to'grip the squared end .with. freedom for slight turning movement of'the latter therein. Notches or cross grooves 25 cut in the inner. ends of the sides 19 of the recesses or grooves 18provide stop shoulders 2.7.atthe outer endsof the sides 23 of thegrooves 22, against which the end portions or shoulders 28ofthecylindrical shank portions 20 of the .rea1ner2l seats whenv the tool is inserted in the chuck. I

In practice, when the work is extremely heavy the resistance set up causes the tool shank to slip or turn relatively to the smooth gripping faces or sidesof thejaws but this movement is stopped and the tool is there after positively driven when the squared end of the tool reaches the limit of its rotary movement in the recesses .22 and becomes locked. This provision for limited relative movement of the tool with respect .to the clamping jaws is. important in that it ohviates the necessity of serrating the gripping faces of the jaws with consequent damaging effect upon the reamer or other tool.

' From the foregoing it will be seen that each jaw is adapted tofirstgrip the cylin drical portion 20'of the tool shank, with frictional driving effect and finally grip the squared end portion 24 with positive locking driving efl'ect. A double or differential driving effect is thus obtained and: the strain is distributed throughout the length of the tool shank which receives the greatest stress at its squared end where it 1s=most adaptable to resist tearing or shearing action of the jaws.

lVith the chuck parts in Figure 4 position with the awseforcedoutwardly. :by the expansive action of spring 13, screwing up of the cap 4 will cause the conicalnose of the latter to engage the conical outer end or nose 26 formed on each jaw. Continued inward movement of the cap moves the outer ends of the aws inwardly, and as the spring 13 effective centering and gripping of th'; tr'lai'i shank.

Having thus described my invention what I claim as my invention is:

In a chuck, a pair of tool-shank engaging LAWRENCE o. "BEARD. 

